It is when two or more different substances which are mixed
PH + pOH = 14
pH + 0.253 = 14
pH = 14 - 0.253
pH = 13.747
[ H+] = 10 ^ -pH
[ H+ ] = 10 ^- 13.747
[ H+ ] = 1.790x10⁻¹⁴ M
hope this helps!
There are 1,000 mm in a meter so times 1.2 by 1,000 and you get 1,200.
Now since he wants it in three equal pieces divide 1,200/3 and you get 400.
So your answer is: 400 mm
That would be C, a cast. It is similar to the process of filling a mold with foam or clay, which is also called a cast.